Limits...
The between and within day variation in gross efficiency.

Noordhof DA, de Koning JJ, van Erp T, van Keimpema B, de Ridder D, Otter R, Foster C - Eur. J. Appl. Physiol. (2010)

Bottom Line: PI was calculated by multiplying VO2 with the oxygen equivalent.The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected.Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Movement Sciences, VU University-Amsterdam, Van Der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands. d.noordhof@fbw.vu.nl

ABSTRACT
Before the influence of divergent factors on gross efficiency (GE) [the ratio of mechanical power output (PO) to metabolic power input (PI)] can be assessed, the variation in GE between days, i.e. the test-retest reliability, and the within day variation needs to be known. Physically active males (n = 18) performed a maximal incremental exercise test to obtain VO2max and PO at VO2max (PVO2max), and three experimental testing days, consisting of seven submaximal exercise bouts evenly distributed over the 24 h of the day. Each submaximal exercise bout consisted of six min cycling at 45, 55 and 65% PVO2max, during which VO(2) and RER were measured. GE was determined from the final 3 min of each exercise intensity with: GE = (PO/PI) x 100%. PI was calculated by multiplying VO2 with the oxygen equivalent. GE measured during the individually highest exercise intensity with RER <1.0 did not differ significantly between days (F = 2.70, p = 0.08), which resulted in lower and upper boundaries of the 95% limits of agreement of 19.6 and 20.8%, respectively, around a mean GE of 20.2%. Although there were minor within day variations in GE, differences in GE over the day were not significant (F = 0.16, p = 0.99). The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected. Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

Show MeSH

Related in: MedlinePlus

The circadian rhythm in resting body temperature of day 1, day 2, and day 3. The solid and broken line are the circadian rhythms in, respectively, pre- and post-exercise body temperature
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2908447&req=5

Fig4: The circadian rhythm in resting body temperature of day 1, day 2, and day 3. The solid and broken line are the circadian rhythms in, respectively, pre- and post-exercise body temperature

Mentions: To investigate if possible circadian rhythms in physiological variables during exercise were due to changes in BT, BT was measured before and immediately after each exercise bout. It was not possible to perform a repeated measures ANOVA on BT data to test if BT changed significantly between different times of the day, because of missing values, which were caused by the premature excretion of the temperature pill in several subjects. To test if there existed a circadian rhythm in BT a least square Cosinor regression analysis was performed. A repeated measures ANOVA was executed to examine if the amplitudes of the best fit Cosinor functions differed significantly from zero (F = 55.4, p < 0.001). Post hoc analysis with a Bonferroni adjustment (α = 0.017) showed that the amplitude of the best fit Cosinor function of BT of day 1, day 2, and day 3 were all significantly different from zero (F = 146, p < 0.001; F = 142, p < 0.001; F = 163, p < 0.001) (Table 1). There was no difference in the amplitude of the best fit Cosinor function of BT before and immediately after exercise (F = 0.30, p = 0.59). The mean minimum BT was estimated to be 36.54 ± 0.18°C for day 1 and was reached at 03:42 ± 3:14 h, the minimum BT was 36.6 ± 0.21 and 36. 6 ± 0.19°C during day 2 and 3 and was reached at 02:46 ± 6:32 and 03:57 ± 4:31 h, respectively. The maximum BTs were estimated to be 37.5 ± 0.30, 37.3 ± 0.25, and 37.3 ± 0.18°C, reached at 17:07 ± 3:11, 17:35 ± 1:45, and 17:22 ± 2:13 h, at, respectively, day 1, day 2, and day 3. Immediately after the exercise bout the maximum BTs were 38.2 ± 0.36, 38.2 ± 0.24, and 38.2 ± 0.27°C, reached at 16:26 ± 3:49, 17:38 ± 4:23, and 17:12 ± 2:56 h, at, respectively, day 1, day 2, and day 3 (Fig. 4).Table 1


The between and within day variation in gross efficiency.

Noordhof DA, de Koning JJ, van Erp T, van Keimpema B, de Ridder D, Otter R, Foster C - Eur. J. Appl. Physiol. (2010)

The circadian rhythm in resting body temperature of day 1, day 2, and day 3. The solid and broken line are the circadian rhythms in, respectively, pre- and post-exercise body temperature
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908447&req=5

Fig4: The circadian rhythm in resting body temperature of day 1, day 2, and day 3. The solid and broken line are the circadian rhythms in, respectively, pre- and post-exercise body temperature
Mentions: To investigate if possible circadian rhythms in physiological variables during exercise were due to changes in BT, BT was measured before and immediately after each exercise bout. It was not possible to perform a repeated measures ANOVA on BT data to test if BT changed significantly between different times of the day, because of missing values, which were caused by the premature excretion of the temperature pill in several subjects. To test if there existed a circadian rhythm in BT a least square Cosinor regression analysis was performed. A repeated measures ANOVA was executed to examine if the amplitudes of the best fit Cosinor functions differed significantly from zero (F = 55.4, p < 0.001). Post hoc analysis with a Bonferroni adjustment (α = 0.017) showed that the amplitude of the best fit Cosinor function of BT of day 1, day 2, and day 3 were all significantly different from zero (F = 146, p < 0.001; F = 142, p < 0.001; F = 163, p < 0.001) (Table 1). There was no difference in the amplitude of the best fit Cosinor function of BT before and immediately after exercise (F = 0.30, p = 0.59). The mean minimum BT was estimated to be 36.54 ± 0.18°C for day 1 and was reached at 03:42 ± 3:14 h, the minimum BT was 36.6 ± 0.21 and 36. 6 ± 0.19°C during day 2 and 3 and was reached at 02:46 ± 6:32 and 03:57 ± 4:31 h, respectively. The maximum BTs were estimated to be 37.5 ± 0.30, 37.3 ± 0.25, and 37.3 ± 0.18°C, reached at 17:07 ± 3:11, 17:35 ± 1:45, and 17:22 ± 2:13 h, at, respectively, day 1, day 2, and day 3. Immediately after the exercise bout the maximum BTs were 38.2 ± 0.36, 38.2 ± 0.24, and 38.2 ± 0.27°C, reached at 16:26 ± 3:49, 17:38 ± 4:23, and 17:12 ± 2:56 h, at, respectively, day 1, day 2, and day 3 (Fig. 4).Table 1

Bottom Line: PI was calculated by multiplying VO2 with the oxygen equivalent.The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected.Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Movement Sciences, VU University-Amsterdam, Van Der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands. d.noordhof@fbw.vu.nl

ABSTRACT
Before the influence of divergent factors on gross efficiency (GE) [the ratio of mechanical power output (PO) to metabolic power input (PI)] can be assessed, the variation in GE between days, i.e. the test-retest reliability, and the within day variation needs to be known. Physically active males (n = 18) performed a maximal incremental exercise test to obtain VO2max and PO at VO2max (PVO2max), and three experimental testing days, consisting of seven submaximal exercise bouts evenly distributed over the 24 h of the day. Each submaximal exercise bout consisted of six min cycling at 45, 55 and 65% PVO2max, during which VO(2) and RER were measured. GE was determined from the final 3 min of each exercise intensity with: GE = (PO/PI) x 100%. PI was calculated by multiplying VO2 with the oxygen equivalent. GE measured during the individually highest exercise intensity with RER <1.0 did not differ significantly between days (F = 2.70, p = 0.08), which resulted in lower and upper boundaries of the 95% limits of agreement of 19.6 and 20.8%, respectively, around a mean GE of 20.2%. Although there were minor within day variations in GE, differences in GE over the day were not significant (F = 0.16, p = 0.99). The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected. Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

Show MeSH
Related in: MedlinePlus